The present invention relates to the use of at least one unpowered induction choke to form an electrical circuit in a piping structure. In one aspect, it relates to providing power and/or communications to a device downhole in a borehole of a well using an electrical circuit formed in a piping structure by using at least one unpowered induction choke.
This application claims the benefit of the U.S. Provisional Applications in the following table, all of which are hereby incorporated by reference:
The current application shares some specification and figures with the following commonly owned and concurrently filed applications in the following table, all of which are hereby incorporated by reference:
Several methods have been devised to place controllable valves and other devices and sensors downhole on a tubing string in a well, but all such known devices typically use an electrical cable along the tubing string to power and communicate with the devices and sensors. It is undesirable and in practice difficult to use a cable along the tubing string either integral with the tubing string or spaced in the annulus between the tubing and the casing because of the number of failure mechanisms are present in such a system. Other methods of communicating within a borehole are described in U.S. Pat. Nos. 5,493,288; 5,576,703; 5,574,374; 5,467,083; and 5,130,706.
U.S. Pat. No. 6,070,608 describes a surface controlled gas lift valve for use in oil wells. Methods of actuating the valve include electro-hydraulic, hydraulic, and pneumo-hydraulic. Sensors relay the position of the variable orifice and critical fluid pressures to a panel on the surface. However, when describing how electricity is provided to the downhole sensors and valves, the means of getting the electric power/signal to the valves/sensors is described as an electrical conduit that connects between the valve/sensor downhole and a control panel at the surface. U.S. Pat. No. 6,070,608 does not specifically describe or show the current path from the device downhole to the surface. The electrical conduit is shown in the figures as a standard electrical conduit, i.e., an extended pipe with individual wires protected therein, such that the pipe provides physical protection and the wires therein provide the current path. But such standard electrical conduits can be difficult to route at great depths, around turns for deviated wells, along multiple branches for a well having multiple lateral branches, and/or in parallel with coiled production tubing. Hence, there is a need for a system and method of providing power and communications signals to downhole devices without the need for a separate electrical conduit filled with wires and strung along side of production tubing.
U.S. Pat. No. 4,839,644 describes a method and system for wireless two-way communications in a cased borehole having a tubing string. However, this system describes a downhole toroid antenna for coupling electromagnetic energy in a waveguide TEM mode using the annulus between the casing and the tubing. This toroid antenna uses an electromagnetic wave coupling that requires a substantially nonconductive fluid (such as refined, heavy oil) in the annulus between the casing and the tubing as a transmission medium, as well as a toroidal cavity and wellhead insulators. Therefore, the method and system described in U.S. Pat. No. 4,839,644 is expensive, has problems with brine leakage into the casing, and is difficult to use for downhole two-way communication. Thus, a need exists for a better system and method of providing power and communications signals to downhole devices without the need for a nonconductive fluid to be present in the annulus between the casing and tubing.
Other downhole communication concepts, such as mud pulse telemetry (U.S. Pat. Nos. 4,648,471 and 5,887,657), have shown successful communication at low data rates but are of limited usefulness as a communication scheme where high data rates are required or it is undesirable to have complex, mud pulse telemetry equipment downhole. Still other downhole communication methods have been attempted, see U.S. Pat. Nos. 5,467,083; 4,739,325; 4,578,675; 5,883,516; and 4,468,665. Hence, there is a need for a system and method of providing power and communications signals to downhole devices at higher data rates and with available power to operate a downhole device.
It would, therefore, be a significant advance in the operation of petroleum wells if tubing, casing, liners, and/or other conductors installed in wells could be used for the communication and power conductors to control and operate devices and sensors downhole in a petroleum well.
Induction chokes have been used in connection with sensitive instrumentation to protect against surges and stray voltage. For example, most personal computers have some sort of choke incorporated into its AC power cord for such protection. Such protection chokes work well for their intended purpose, but do not operate to define a power or communication circuit.
All references cited herein are incorporated by reference to the maximum extent allowable by law. To the extent a reference may not be fully incorporated herein it is incorporated by reference for background purposes, and indicative of the knowledge of one of ordinary skill in the art.
The problems and needs outlined above are largely solved and met by the present invention. In accordance with a first aspect of the present invention, a current impedance device for routing a time-varying electrical current in a piping structure is provided. The current impedance device comprises an induction choke that is generally concentric about a portion of the piping structure, such that during operation a voltage potential forms between the piping structure and an electrical return when the time-varying electrical current is transmitted through and along the portion of the piping structure, and such that during operation part of the current can be routed through a device electrically connected to the piping structure due to the voltage potential formed. The induction choke may be unpowered and may comprise a ferromagnetic material. The induction choke can be generally cylindrical shaped with a generally cylindrical shaped borehole formed therethrough. The choke may be enclosed within an insulating shell.
In accordance with a second aspect of the present invention, a system for defining an electrical circuit is provided. The system comprises a piping structure, a source of time-varying current, an induction choke, a device, and an electrical return. The piping structure comprises a first location, a second location, and an electrically conductive portion extending between the first and second locations. The first and second locations are distally spaced along the piping structure. The source of time-varying current is electrically connected to the electrically conductive portion of the piping structure at a location along the first location. The induction choke is located about part of the electrically conductive portion of the piping structure. The device comprises two terminals. A first of the device terminals is electrically connected to the electrically conductive portion of the piping structure. The electrical return electrically connects between a second of the device terminals and the source to complete the electrical circuit. When applying the system in a petroleum well for example, the first location is near the surface and the second location is downhole in a borehole of the well.
In an embodiment of the system in accordance with the second aspect of the present invention, the choke can be located along the second location, and the electrical connection location for the first device terminal can be between the choke and the electrical connection location for the source.
Another embodiment of the system in accordance with the second aspect can further comprise a second induction choke located about a portion of the piping structure along the first location, such that the source is connected to the piping structure between the chokes. Yet another embodiment of the system further comprises an electric power transformer located about a portion of the piping structure between the electrical connection location for the source and the second choke.
Still another embodiment of the system in accordance with the second aspect can further comprise an electric power transformer located about a portion of the piping structure between the electrical connection location for the source and the choke. The electric power transformer may comprise a ferromagnetic toroid wound by wire such that the wire is generally parallel to a central axis of the toroid when wound about the toroid.
In a further embodiment of the system in accordance with the second aspect of the present invention, the choke is located along the first location, the electrical connection location for the first device terminal is along the second location, and the electrical connection location for the source is between the choke and the electrical connection location for the first device terminal. A still further embodiment can further comprise a second induction choke located about a portion of the piping structure along the second location, such that the electrical connection location for the source is between the chokes, and such that the electrical connection location for the first device terminal is between the second choke and the electrical connection location for the source.
Another embodiment of the system in accordance with the second aspect further comprises an electric power transformer located about a portion of the piping structure, such that the electrical connection location for the source is between the choke and the transformer.
In accordance with a third aspect of the present invention, a system for providing power or communications to a remote device is provided. The system comprises a piping structure, an induction choke, an electric power transformer, a source of time-varying current, a device, and an electrical return. The piping structure comprises a first location, a second location, and an electrically conductive portion extending between the first and second locations. The first and second locations are distally spaced along the piping structure. The induction choke is located about a portion of the piping structure. The source of time-varying current is electrically connected to the electrically conductive portion of the piping structure for supplying primary electrical current. The transformer is located about a portion of the piping structure and adapted to form a secondary coil for supplying secondary electrical current corresponding to the primary electrical current when the primary electrical current is flowing in the electrically conductive portion of the piping structure, wherein the electrically conductive portion of the piping structure acts as a primary coil. The electrical return electrically connects between the electrically conductive portion of the piping structure and the source to complete an electrical circuit, such that the transformer is located between the electrical connection location for the source and the electrical connection location for the electrical return along the piping structure. The device is electrically connected to the transformer for receiving the secondary electrical current. Hence, when the system is operable, the device can receive power, and/or send or receive communication signals, via the transformer and the electrical circuit formed.
In an embodiment of the system in accordance with a third aspect of the present invention, the choke can be located along the first location, and the electrical connection location for the source can be located between the choke and the transformer. Also, the transformer can be located along the first location or the second location. The embodiment can further comprise a second induction choke located about a portion of the piping structure along the second location, such that the transformer is located between the chokes. In another embodiment of the system in accordance with the third aspect, the choke can be located along the second location, and the electrical connection location for the source can be located along the first location. The electrical connection location for the electrical return can be located between the transformer and the choke, or the choke can be located between the transformer and the electrical connection location for the electrical return. The embodiment can further comprise an electrical insulator along the first location, such that the electrical connection location for the source is between the insulator and the transformer. The insulator can comprise an insulated hanger.
In accordance with a fourth aspect of the present invention, a petroleum well for producing petroleum products is provided. The petroleum well comprises a piping structure and an electrical circuit. The piping structure comprises a first location, a second location, and an electrically conductive portion extending between the first and second locations. The first and second locations are distally spaced along the piping structure. The electrical circuit comprises the electrically conductive portion of the piping structure, a source of time-varying current, an induction choke, a device, and an electrical return. The source of time-varying current is electrically connected to the electrically conductive portion of the piping structure at a location along the first location. The induction choke is located about part of the electrically conductive portion of the piping structure. The device comprises two terminals, a first of the device terminals being electrically connected to the electrically conductive portion of the piping structure. The electrical return electrically connects between a second of the device terminals and the source to complete the electrical circuit.
The piping structure can comprise at least a portion of a production tubing string, at least a portion of a pumping rod, at least a portion of a well casing, at least a portion of at least one branch forming a lateral extension of a well, at least a portion of an oil refinery piping network, at least a portion of above surface refinery production pipes, or any combination thereof. The electrical return can comprise at least a portion of a well casing, at least a portion of an earthen ground, a conductive fluid, a packer, at least a portion of another piping structure of a same well, at least a portion of another piping structure of another well, or any combination thereof.